1. Field of the Invention
The present invention relates to a sound source separation apparatus and a sound source separation method.
2. Description of Related Art
A blind source separation (BSS) technique of separating signals from observed signals in which plural unknown signal sequences are mixed has been proposed. The BSS technique is applied, for example, to sound recognition under noisy conditions. The BSS technique is used to separate sound uttered by a person from ambient noise, the driving sound made by a robot's movement, and the like.
In the BSS technique, spatial propagation characteristics from sound sources are used to separate signals.
For example, a sound source separation system described in Japanese Patent No. 4444345 is defined by a separation matrix indicating correlations between input signals and sound source signals, and a process is repeatedly performed of updating a current separation matrix into a subsequent separation matrix so that a subsequent value of a cost function for evaluating a degree of separation of the sound source signals is closer to the minimum value than to a current value thereof.
The degree of update of the separation matrix is adjusted to increase as the current value of the cost function increases and to decrease as rapidly as the current gradient of the cost function.
The sound source signals are separated with high precision on the basis of input signals to plural microphones and the optimal separation matrix.